| Portalegre to Nuth | 1,027.69 mi (1,653.90 km) |
| Portalegre to Oegstgeest | 1,054.61 mi (1,697.23 km) |
| Portalegre to Oirschot | 1,040.40 mi (1,674.36 km) |
| Portalegre to Oisterwijk | 1,041.96 mi (1,676.87 km) |
| Portalegre to Oldebroek | 1,106.87 mi (1,781.33 km) |
| Portalegre to Oldenzaal | 1,128.91 mi (1,816.80 km) |
| Portalegre to Ommen | 1,124.55 mi (1,809.79 km) |
| Portalegre to Oosterend | 1,140.71 mi (1,835.79 km) |
| Portalegre to Oosterhout | 1,035.66 mi (1,666.74 km) |
| Portalegre to Oosterwolde | 1,145.97 mi (1,844.27 km) |
| Portalegre to Oostzaan | 1,079.03 mi (1,736.53 km) |
| Portalegre to Opmeer | 1,095.34 mi (1,762.79 km) |
| Portalegre to Oss | 1,060.41 mi (1,706.57 km) |
| Portalegre to Oud-Beijerland | 1,032.80 mi (1,662.13 km) |
| Portalegre to Oudenbosch | 1,023.76 mi (1,647.58 km) |
